The present invention relates to ink-jet printers, and more particularly to improvements in a common cartridge platform used for different printheads.
Ink-jet printers are in widespread use today for printing functions in personal computer, facsimile and other applications. Such printers typically include replaceable print cartridges which hold a supply of ink and carry the ink-jet printhead. The cartridge typically is secured into a printer carriage which supports one or a plurality of cartridges above the print medium, and traverses the medium in a direction transverse to the direction of medium travel through the printer. Electrical connections are made to the printhead by flexible wiring circuits attached to the outside of the cartridge. Each printhead includes a number of tiny nozzles defined in a substrate and nozzle plate structure which are selectively fired by electrical signals applied to interconnect pads to eject droplets of ink in a controlled fashion onto the print medium.
In order to achieve accurate printing quality, each removable cartridge includes datum surfaces which engage against corresponding carriage surfaces to precisely locate the cartridge when inserted into the carriage. In this manner, when a cartridge ink supply is exhausted, the cartridge may be replaced with a fresh cartridge, and the printhead of the new cartridge will be precisely located relative to the carriage.
As improvements have been made in the printhead design or in the ink delivery system for cartridges, it has been the common design practice to design entirely new printer cartridges, incurring expenses in the design and tooling for the new cartridges. Thus, if a new printhead is developed which has different physical size parameters from an earlier design of a printhead, advancing for the sake of example, from a 180 dpi to a 300 dpi resolution, the common practice has been to develop an entirely new cartridge platform to support the new printhead, including different datum surfaces, and indeed, requiring a new printer carriage to support the cartridge.
It is known, in a one-cartridge printer application, to change the nozzle firing frequency, along with the width of the ink feed slots in the substrate die, without changing the datum structure or ink delivery system in an inkjet cartridge, to achieve improved printing performance.
In a series of printers marketed by Hewlett-Packard Company, the "Deskjet" series, two different cartridges are available for use in the same printer, one having a relatively lower ink capacity than the other. In this case, the high and low ink capacity cartridges employ the same datum structure, but different ink delivery systems.
In one instance, even though the shape and configuration of the nozzle plate and substrate have not been changed, the size of nozzle plate orifices and substrate firing resistors have been changed, to adapt a particular ink-jet cartridge design to a new ink of different viscosity. In another instance, an existing cartridge designed for black ink was modified to operate with color ink, by changing the nozzle orifice size and substrate firing resistor size, reducing the number of active nozzles, and making slight dimensional variations to the substrate die and nozzle plate, in order to adapt the printhead to different fluidic properties of another ink, while using the same datum structure and ink reservoir system.
Commonly assigned U.S. Pat. No. 4,872,027 describes an ink-jet printer having identifiable interchangeable printheads which are interchangeably attachable to the printer carriage. The heads are provided with individual codes read by the printer control system to reconfigure its control functions to suit the control requirements of the identified head.
It is therefore an object of this invention to provide a method for designing a cartridge which incorporates a common datum structure and ink delivery system from another cartridge design to support a different printhead with different printing characteristics, thereby allowing the development expenses and tooling costs for the common structure to be spread over more than one cartridge.
A further object is to provide a family of ink cartridges, each of which employs a common datum structure and common ink reservoir system but with physically different printheads.